Device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines

ABSTRACT

A device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, in which a main thread takeup lever is controlled in such a way that it can be moved up and down about a fulcrum. A spring lever is movable together with this main thread takeup lever and is mounted on the fulcrum thereof. A torsion spring urges the spring lever against a stop mounted in a permanent position in the machine. The upper thread in course of being unwound is additionally guided by the spring lever on the upstream side of the main thread takeup lever. The spring lever is preceded by a blocking device which can be moved into the path of motion of said spring lever.

United States Patent Trageser 1 Feb. 15, 1972 54] DEVICE FOR THE OCCASIONAL 2,099,574 11/1937 Rosenman et al ..112/241 x OMISSION 0 BACKSTITCHES 0 3.428.009 2/1969 Moro ..l l2/255 AUTOMATICALLY CONTROLLED QUILTING AND EMBROIDERY MACHINES lnventor: Ludwig Trageser, 32 Van Bargen Strasse, Hamburg-Wandsbek, Germany Filed: Mar. 18, 1970 Appl. No.: 20,658

Held Search I l2l57, 96, 241-250, 112/254, 255

References Cited UNITED STATES PATENTS Rosenman ..l I 2/ 24 l Primary Examiner-Patrick D. Lawson Assistant Examiner-Geo. V. Larkin Attorney-Markva & Smith [57] ABSTRACT A device for the occasional omision of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, in which a main thread takeup lever is controlled in such a way that it can be moved up and down about a fulcrum. A spring lever is movable together with this main thread takeup lever and is mounted on the fulcrum thereof. A torsion spring urges the spring lever against a stop mounted in a permanent position in the machine. The upper thread in course of being unwound is additionally guided by the spring lever on the upstream side of the main thread takeup lever. The spring lever is preceded by a blocking device which can be moved into the path of motion of said spring lever.

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INVENTOR LUDW/G TRAGESER BACKGROUND OF THE INVENTION This invention relates to a device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, in which the main thread takeup lever is controlled in such a way that it can be moved up and down.

Automatic embroidery machines operate, like quilting machines, with an upper thread and a lower thread. The lower thread is wound onto a bobbin and placed in a bobbin case with adjusting means for the thread-braking action (thread tension). The bobbin case with the lower thread fits into a gripper system of which the purpose is to grip the upper thread loop forming on the needle and to force it round the bobbin case, thus tying the upper thread and the lower thread (forming a stitch). During the passage of the bobbin case a certain thread length is required for the loop of the upper thread, the said length being released by the descending movement of the takeup lever (thread lever) as soon as the point of the gripper has engaged the thread loop. Immediately after the passage of the bobbin case the thread lever pulls down the loop of the upper thread.

For the omission of stitches, processes are known which involve complicated and compact devices on the gripper system or on the main thread takeup lever and which can only operate with the exertion of considerable force and have not proved satisfactory in practice.

Systems are also known in which blank stitches" are produced artificially. For this purpose the needle bar is turned through an angle of about 90 so that the point of the gripper will bypass the thread loop forming at the eye of the needle. This method of omitting stitches may involve the drawback that the thread loops turned away get caught and lead to thread breakages.

SUMMARY OF THE INVENTION In order to be certain of obviating faulty operations on automatically controlled embroidery machines, the invention aims at preventing the formation of a thread loop at the eye of the needle, when the embrodiery machine needle is in the lowest position, by automatically bringing about a considerable increase in the tension of the upper thread.

To attain this object the present invention provides a device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, which comprises a main thread takeup lever so controlled that is can move up and down about a fulcrum in a machine head; a spring lever movable together with said main thread takeup lever and mounted on the fulcrum thereof, and a torsion spring urging said spring lever against a stop mounted in a permanent position in said machine head, an upper thread in course of being unwound being additionally guided by the spring lever on the upstream side of the main thread takeup lever and the spring lever being preceded by a blocking device capable of being moved into the path of motion of said spring lever.

The blocking device may comprise a controllable lifting magnet and a supporting lever influenced by said lifting magnet and equipped with a restoring spring, said supporting lever being swingable about a pivot and preventing said spring lever from moving. The torsion spring of the spring lever is preferably made adjustable to the thread thickness and to the type of stitch.

BRIEF DESCRIPTION OF THE DRAWING A preferred embodiment of the invention will now be described by way of example and with reference to the accompanying drawing, in which:

FIG. I is a side view of an embroidery head in the position for the formation of a stitch;

FIG. 2 is a side view of the embroidery head in the position for the omission of stitches, and

FIG. 3 is a front view of the embroidery head as shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the usual embroidery machines the movement between the needle 12 and the gripper I4 is coordinated in such a way that for the formation of stitches the point 20 of the gripper l4 takes up the loop formed in the upper thread by the needle l2, in which process the gripper I4 rotates in the direction shown by the arrow l9. The needle I2 is secured in a needle bar II, with which it performs a to-and-fro movement.

A main thread takeup lever 2 is pivotally mounted on fulcrum I which in turn is mounted in the machine head 22. The takeup lever 2 is moved up and down by a cam 21 driven control shaft l5 of the embroidery machine, which cam is engaged by a cam follower 23 attached to the takeup lever 2. A spring lever 5 is also mounted on the fulcrum I and is biased by a torsion spring 3 towards a stop 4 mounted in a fixed position in the machine head. The tension in the tension spring 3 may be adjusted by a thumb screw 24.

In normal stitch formation the main thread takeup lever 2 and the spring lever 5 move up and down almost parallel, the spring lever 5 being situated a few millimeters higher up than the main thread takeup lever 2. The spring lever 5 maintains a slight tension in the upper thread at all times. The movement of the spring lever is governed solely by the thread tension and by the amount of thread required for the formation of the upper thread loop on the gripper system.

Selected backstitches are omitted by blocking means. When a backstitch is to be omitted a lifting magnet 10 is supplied, when the main thread takeup lever 2 is in the highest position, with a control impulse, the core 16 of the magnet I0 then being retracted toward the right as viewed in FIG. I causing the end I7 ofa supporting lever B pivotably mounted at 7 to be rotated and the free end I8 of the lever to be pivoted into the path of motion of the spring lever 5. The descending movement of the spring lever 5 which is parallel to the main thread takeup lever 2 is then prevented, and the considerably increasing force of the spring lever 5 keeps the upper thread in the lowest needle position (FIG. 3) so taut that no thread loop can form at the eye of the needle I2, any connection forming a stitch between the upper and lower thread thus likewise being impossible.

The stitch omission process is terminated as soon as the lifting magnet [0 receives appropriate control impulses and returns to its initial position. The supporting lever 8 will then have been tilted out of the path of movement of the spring lever 5 by means of a restoring spring 9. The control impulses for the lifting magnet are provided, in a manner known per se, by ajacquard card controlling the embroidery machine, or by similar means.

The advantages offered by the invention reside in the fact that thread loops are avoided in the stitch omission operation and that the otherwise customary connecting stitches between the separate embroidered lots are eliminated and these can be more easily cutout. Furthermore, backstitches or embroidery stitches can be produced to any desired length by joining up a number of normal stitches with which the intermediate stitches are automatically omitted. This system thus provides the embroidery industry a wide variety of new possibilities for the designing of patterns and the production of embroidery stitches on economical lines.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive.

What is claimed is:

I. A device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, comprising a. a main thread takeup lever so controlled that it can move up and down about a fulcrum in a machine head;

b. a spring lever movable together with said main thread takeup lever and mounted on the fulcrum thereof,

c. a torsion spring urging said spring lever against a stop mounted in a permanent position in said machine head, an upper thread in course of being unwound being guided by the main thread takeup lever and the spring lever located on the upstream side of the main thread takeup lever, and

d. a blocking device capable of being moved into and out of the path of motion of said spring lever.

2. A device in accordance with claim 1, wherein the blocking device comprises a controllable lifting magnet and a supporting lever influenced by said lifting magnet and equipped with a restoring spring said supporting lever being swingable about a pivot and preventing said spring lever from moving when in the path of motion ofsaid spring lever.

3. A device in accordance with claim 1, wherein the torsion spring of the spring lever is adjustable to the thread thickness and to the nature of the embroidery to be effected.

4. A device for causing omission of backstitches on automatic embroidery machines comprising a. means supporting a needle b. a takeup lever for supporting the thread to the point of said needle and movable towards and away from the point of said needle c. a spring lever movable with said takeup lever for supporting said thread between said takeup lever and needle, and

d. blocking means adapted for movement into and out of the path of motion of said Spring lever,

. whereby when said blocking means is in the path of mo tion of said spring lever said thread is maintained taut by said spring lever so that no thread loop can form at the point of the needle thereby preventing a stitch from being formed.

test: 

1. A device for the occasional omission of backstitches on automatically controlled quilting and embroidery machines, particularly on automatic embroidery machines, comprising a. a main thread takeup lever so controlled that it can move up and down about a fulcrum in a machine head; b. a spring lever movable together with said main thread takeup lever and mounted on the fulcrum thereof, c. a torsion spring urging said spring lever against a stop mounted in a permanent position in said machine head, an upper thread in course of being unwound being guided by the main thread takeup lever and the spring lever located on the upstream side of the main thread takeup lever, and d. a blocking device capable of being moved into and out of the path of motion of said spring lever.
 2. A device in accordance with claim 1, wherein the blocking device comprises a controllable lifting magnet and a supporting lever influenced by said lifting magnet and equipped with a restoring spring, said supporting lever being swingable about a pivot and preventing said spring lever from moving when in the path of motion of said spring lever.
 3. A device in accordance with claim 1, wherein the torsion spring of the spring lever is adjustable to the thread thickness and to the nature of the embroidery to be effected.
 4. A device for causing omission of backstitches on automatic embroidery machines comprising a. means supporting a needle b. a takeup lever for supporting the thread to the point of said needle and movable towards and away from the point of said needle c. a spring lever movable with said takeup lever for supporting said thread between said takeup lever and needle, and d. blocking means adapted for movement into and out of the path of motion of said spring lever, e. whereby when said blocking means is in the path of motion of said spring lever said thread is maintained taut by said spring lever so that no thread loop can form at the point of the needle thereby preventing a stitch from being formed. 